Direct type backlight unit

ABSTRACT

A direct type backlight unit includes a metal housing having a base, at least one metal supporting pin and a buffer element. The metal supporting pin is formed integrally on the base and protrudes upwardly therefrom for supporting an optical film disposed upon the backlight unit, and the buffer element is disposed between the metal supporting pin and the optical film so as to prevent the metal supporting pin from damaging the optical film.

CROSS REFERENCE

This application is a divisional application of U.S. application Ser.No. 10/925,958 filed Aug. 26, 2004, now U.S. Pat. No. 7,156,549, whichclaims priority from Taiwan Patent Application No. 093100280 filed Jan.6, 2004. All of the above applications are incorporated herein byreference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention generally relates to a direct type backlight unit, andmore particularly to a direct type backlight unit having a supportingpin formed integrally therein.

2. Description of the Related Art

Due to the advance of electronic technology, especially for thepopularity of portable electronic products, the requirements of light,compact and low-energy consuming display are gradually increasing. Withthe advantages of low-energy consuming, low-heat dissipation, lightweight and non-luminescence, liquid crystal displays (LCD) have beenwidely used in the electronic products and even have replaced thetraditional CRT displays.

In general, a liquid crystal display usually comprises a backlight unitfor providing light to its liquid crystal panel. However, the liquidcrystal display may use different kinds of backlight units depending onits use and size. These backlight units mainly include two types, i.e. adirect back light type (or direct type) and an edge light type. Thepresent invention herein is related to the direct type backlight unit,and thus only the direct type backlight unit will be described infollowing descriptions.

Referring to FIG. 1, it shows an exploded schematic view of a liquidcrystal display 100 having a direct type backlight unit in the priorart. The liquid crystal display 100 includes a backlight unit 102, a setof optical films 104, a liquid crystal panel 106 and a frame 108. Thebacklight unit 102 is disposed under the liquid crystal panel 106 fordistributing the light from a light source uniformly over the surface ofthe liquid crystal panel 106. The backlight unit 102 comprises a metalhousing 103 and lamps 100, such as cold cathode fluorescent lamps(CCFL), disposed at the base of the metal housing 103. The set ofoptical films 104 is disposed between the backlight unit 102 and theliquid crystal panel 106 and includes a diffuser 104 a disposed upon thebacklight unit 102 and a plurality of optical sheets, such as adiffusing sheet 140 b and a prism sheet 140 c, disposed on the diffuser104 a. The frame 108 is disposed upon the liquid crystal panel 106 andthe set of optical films 104 and connected to the backlight unit 102 soas to fix the liquid crystal panel 106 and the set of optical films 104on the backlight unit 102. FIG. 2 shows a cross-sectional view of theassembled liquid crystal display 100 taken along line A-A in FIG. 1.

The lamps 110 are spacedly disposed on the cavity 105 formed by themetal housing 103 and positioned under the display area of the liquidcrystal panel 106 so as to distribute the light uniformly over thesurface of the liquid crystal panel 106. Further, since the lamps 110need to keep a certain distance from the diffuser 104 a, at least onesupporting pin 112 is required to be disposed on the base 103 a of themetal housing 103 for supporting the diffuser 104 a such that the lamps110 can keep a fixed distance from the diffuser 104 a.

In the prior art, the supporting pin 112 is a white or transparentconical pin, which is typically made of polycarbonate (PC) or PMMA bythe injection molding process. In addition, the base 103 a of the metalhousing 103 is covered with an adhesive film (not shown), and thesupporting pin 112 adheres to the base 103 a of the metal housing 103 bythe adhesive film.

However, the reliability of such an adhesion manner to fix thesupporting pin 112 on the base 103 a of the metal housing 103 is usuallypoor.

Accordingly, the present invention provides a direct type backlight unithaving a supporting pin formed integrally therein so as to solve thereliability problem of the supporting pin.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a direct typebacklight unit having a supporting pin formed integrally therein so asto solve the reliability problem of the supporting pin.

It is another object of the present invention to provide a direct typebacklight unit having a supporting pin formed integrally therein whereinthe supporting pin has a buffer element disposed thereon so as toprevent itself from damaging an optical film.

In order to achieve the above objects, the present invention provides adirect type backlight unit comprising a metal housing, at least onemetal supporting pin and a buffer element. The metal supporting pin isformed integrally on a base of the metal housing and protrudes upwardlyfrom the base for supporting an optical film disposed upon the backlightunit, and the buffer element is disposed between the metal supportingpin and the optical film so as to prevent the metal supporting pin fromdamaging the optical film.

According to the direct type backlight unit of the present invention,the metal supporting pin is formed integrally on the base of the metalhousing by the press forming process so as to solve the reliabilityproblem of the supporting pin. Further, the buffer element is preferablya white buffer cap and caps on the metal supporting pin so as to preventthe metal supporting pin from damaging the optical film.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, advantages, and novel features of the present inventionwill become more apparent from the following detailed description whentaken in conjunction with the accompanying drawings.

FIG. 1 is an exploded schematic view of a liquid crystal display havinga direct type backlight unit in the prior art.

FIG. 2 is a cross-sectional view of the assembled liquid crystal displaytaken along line A-A in FIG. 1.

FIG. 3 is an exploded schematic view of a liquid crystal displayaccording to one embodiment of the present invention.

FIG. 4 is a cross-sectional view of the assembled liquid crystal displaytaken along line B-B in FIG. 3.

FIG. 5 a and 5 b are respectively an enlarged perspective view and anenlarged cross-sectional view for illustrating how the metal supportingpin is to be formed on the metal base.

FIG. 6 is a schematic view of the combined structure of a buffer cap andthe metal pin.

FIG. 7 is a cross-sectional view of a liquid crystal display accordingto another embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 3 is an exploded schematic view of a liquid crystal display 200according to one embodiment of the present invention. The liquid crystaldisplay 200 comprises a liquid crystal panel 206 for producing an imageand a direct type backlight unit 202 for emitting light to the liquidcrystal panel 206. A set of optical films 204 is disposed between thebacklight unit 202 and the liquid crystal panel 206. The set of opticalfilms 204 includes a diffuser 204 a disposed upon the backlight unit 202and a plurality of optical sheets, such as a diffusing sheet 204 b and aprism sheet 204 c, disposed on the diffuser 204 a. The diffuser 204 a isdisposed upon the backlight unit 202 and typically made ofhalf-transparent polyethylene terephthalate (PET), polyethyleneterephthalate, or polycarbonate for further evenly diffusing the lightemitted from the backlight unit 202. Then, the diffused light will passthrough the plurality of optical sheet, such as the diffusing sheet 204b and the prism sheet 204 c, and finally reach the liquid crystal panel206. A frame 208 is disposed upon the liquid crystal panel 206 forfixing the liquid crystal panel 206 and the set of optical films 204upon the backlight unit 202.

Now referring to FIG. 4, it is a cross-sectional view of the assembledliquid crystal display taken along line B-B in FIG. 3. The backlightunit 202 comprises a metal housing 203, which defines a cavity 205 foraccommodating a plurality of lamps 210 such as cold cathode fluorescentlamps (CCFL). The lamps 210 are spacedly disposed on the cavity 205 andpositioned under the set of optical films 204, so as to emit light tothe set of optical films 204 and then distribute it uniformly over thesurface of the liquid crystal panel 206 while the light passes throughthe set of optical films 204.

The metal housing 203 includes a metal base 203 a having a metalsupporting pin 212 disposed thereon and protruding upwardly therefromfor supporting the diffuser 204 a. The metal supporting pin 212 isformed integrally on the metal base 203 a so as to form a firmly fixedstructure, and therefore provided with higher reliability.

FIG. 5 a and 5 b are respectively an enlarged perspective view and anenlarged cross-sectional view for illustrating how the metal supportingpin is to be formed on the metal base. The supporting pin 212 is acylindrical metal pin with a polygonal base 212 a and the metal base 203a has a hole 207 before the metal supporting pin 212 is formedintegrally on the metal base 203 a. Preferably, the diameter of thecylindrical metal pin is about 1.0 mm to 1.5 mm. The hole 207 tapers offfrom the bottom surface toward the top surface of the metal base 203 a(as shown in 5 b), and the cylindrical metal pin 212 is to be insertedinto the hole 207 from the bottom surface and then formed integrally onthe metal base 203 a by the press forming process.

The metal supporting pin 212 according to the present inventionpreferably has a buffer element disposed on its top so as to preventitself from damaging the diffuser 204 a. The buffer element ispreferably made of a material of which the hardness is lower than thatof the diffuser 204 a.

FIG. 6 is a schematic view of the combined structure of a buffer cap 214and the metal supporting pin 212. The buffer element can be made intothe buffer cap 214 shown in FIG. 6, and the buffer cap 214 is preferablywhite and made of silicon rubber. The buffer cap 214 is a cap having adomelike top and defines a combination hole 214 a for capping the top ofthe metal supporting pin 212. FIG. 7 is a cross-sectional view of aliquid crystal display 200 according to another embodiment of thepresent invention. The top of the metal supporting pin 212 is cappedwith the buffer cap 214 shown in FIG. 6, such that the metal supportingpin 212 is prevented from directly contacting the diffuser 204 a andthus can be prevented from damaging the diffuser 204 a by such a manner.

It should be noted that the presently disclosed embodiments are to beconsidered in all respects as illustrative and not restrictive. Forexample, there can be a plurality of metal supporting pins 212 to beevenly formed on the metal base 203 a such that each lamp 210 can keep afixed distance from the diffuser 104 a. In addition, the metalsupporting pin 212 can be formed in any shapes (such as conical shape)and therefore should not be limited to the cylindrical shape asillustrated in above embodiments of the present invention.

According to the direct type backlight unit of the present invention,the metal supporting pin for supporting the diffuser is formedintegrally on the metal housing of the direct type backlight unit by thepress forming process so as to solve the conventional reliabilityproblem of the supporting pin. Further, the metal supporting pin has abuffer element, which is preferably a white buffer cap, disposed thereonso as to prevent the metal supporting pin from damaging the optical filmsupported thereby.

In addition, one feature of the present invention is that a supportingpin for supporting an optical film is formed integrally on the housingof a backlight unit and has a buffer element disposed thereon so as toprevent itself from damaging the supported optical film. Therefore, itshould be understood that the material of the supporting pin and thehousing of the backlight unit in the embodiment of the present inventionare not limited to metal, and the uses of other materials such asplastic, resin or some hardened substances are also falling into thescope of the present invention.

Although the invention has been explained in relation to its preferredembodiment, it is not used to limit the invention. It is to beunderstood that many other possible modifications and variations can bemade by those skilled in the art without departing from the spirit andscope of the invention as hereinafter claimed.

1. A liquid crystal display, comprising: a liquid crystal panel; abacklight unit for emitting light to the liquid crystal panel; and anoptical film disposed between the backlight unit and the liquid crystalpanel; wherein the backlight unit includes: a housing having a base andside walls, said base and side walls together defining a cavity; and asupporting pin protruding upwardly from a middle region of the base;wherein said base has a through hole in the middle region thereof, saidthrough hole having a profile tapering upwardly: said supporting pinincludes a post member sized to be passable through an upper opening ofthe through hole, and a base member connected to a lower end of saidpost member and sized to be not passable though said upper opening; andsaid base member is received in the though hole thereby fixing saidsupporting pin to said base.
 2. The liquid crystal display as claimed inclaim 1, wherein the optical film is a diffuser.
 3. The liquid crystaldisplay as claimed in claim 1, further comprising a plurality of lampsdisposed within the cavity.
 4. The liquid crystal display as claimed inclaim 1, wherein the housing is made of at least one of metal, resin,and plastic.
 5. The liquid crystal display as claimed in claim 1,wherein the supporting pin is formed integrally on the base of thehousing.
 6. The liquid crystal display as claimed in claim 1, whereinthe supporting pin is made of at least one of metal, resin, and plastic.7. The liquid crystal display as claimed in claim 1, wherein thesupporting pin is cylindrical in shape.
 8. The liquid crystal display asclaimed in claim 1, further comprising a buffer element disposed betweenan upper end of the post member and the optical film.
 9. The liquidcrystal display as claimed in claim 8, wherein the buffer element isconfigured to cap the upper end of the supporting pin.
 10. The liquidcrystal display as claimed in claim 8, wherein the buffer element ismade of silicon rubber.
 11. The liquid crystal display as claimed inclaim 8, wherein the buffer element is white.
 12. The liquid crystaldisplay as claimed in claim 8, wherein said buffer element is a caphaving an inner space which receives therein the upper end of said postmember; and a material of said cap is different from a material of saidpost member and softer than a material of said optical film.
 13. Aliquid crystal display, comprising: a liquid crystal panel; a backlightunit for emitting light to the liquid crystal panel; and an optical filmdisposed between the backlight unit and the liquid crystal panel;wherein the backlight unit includes: a housing having a base and sidewalls extending upwardly from a peripheral region of said base, saidbase and said side walls together defining a cavity, the optical filmbeing disposed on top of the side walls of said housing; at least a lampdisposed in said cavity; and at least one supporting pin protrudingupwardly from a middle region of the base and supporting the opticalfilm from below; wherein said base has a through hole in the middleregion thereof, said through hole having a profile tapering upwardly;said supporting pin includes a post member sized to be passable throughan upper opening of the through hole, and a base member connected to alower end of said post member and sized to be not passable though saidupper opening; said base member is received in the though hole therebyfixing said supporting pin to said base; said post member extendsupwardly from said base member through said upper opening into thecavity of said housing and terminates at an upper end on which theoptical film is supported; and said backlight unit further comprises abuffer element being disposed between the upper end of the post memberand the optical film and preventing direct physical contact between theupper end of the post member and the optical film.
 14. The liquidcrystal display as claimed in claim 13, wherein said buffer element is acap having an inner space which receives therein the upper end of saidpost member; and a material of said cap is different from a material ofsaid post member and softer than a material of said optical film.